International Orthopaedics (SICOT) DOI 10.1007/s00264-014-2375-1
ORIGINAL PAPER
Ischio-pubic stress fracture after peri-acetabular osteotomy in patients with hip dysplasia Satoshi Hamai & Yasuharu Nakashima & Mio Akiyama & Umito Kuwashima & Takuaki Yamamoto & Goro Motomura & Masanobu Ohishi & Yukihide Iwamoto
Received: 10 April 2014 / Accepted: 4 May 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Ischio-pubic stress fracture is one of the potential complications after peri-acetabular osteotomy (PAO) in patients with hip dysplasia. The purpose of this study was to examine the prevalence of and risk factors for ischio-pubic fractures following PAO. Methods A total of 296 hips in 275 patients who underwent transposition osteotomy of the acetabulum between 2001 and 2012 were retrospectively reviewed. Patient characteristics and radiographic parameters were compared between patients with and without fracture. Results Fourteen ipsilateral hips (4.7 %) in 14 female patients had fracture of the inferior pubic ramus (11 hips) or the ischial ramus (three hips) on the same side as the surgery at an average of 4.6 weeks after PAO. Multivariate analysis indicated that younger age at operation (odds ratio of 1.43 per five years, p=0.0169) and greater degree of correction (odds ratio of 1.98 per five degrees, p=0.0005) were significantly associated with ischio-pubic fracture as independent risk factors. All fractures healed conservatively with partial weightbearing. Conclusions Younger female patients and greater deformity corrections increased the risk of ischio-pubic stress fracture after PAO.
Keywords Ischio-pubic fracture . Peri-acetabular osteotomy . Transpositional osteotomy of the acetabulum . Hip dysplasia S. Hamai (*) : Y. Nakashima : M. Akiyama : U. Kuwashima : T. Yamamoto : G. Motomura : M. Ohishi : Y. Iwamoto Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan e-mail: [email protected]
Introduction Peri-acetabular osteotomy (PAO) is accepted as an effective treatment for hip dysplasia in young to middle-aged patients [1–9]. PAO can improve acetabular coverage of the femoral head to restore joint congruity and stability, resulting in prevention of further OA deterioration. Previous studies have shown satisfactory intermediate to long-term results of PAO with excellent correction of deformity, pain relief, and restored function [1–7]. We have previously reported outcomes of transposition osteotomy of the acetabulum, a spherical osteotomy with a transtrochanteric approach. The survival rate with THA conversion or progress to the end stages of OA as the end points was 94 % at ten years after operation [8, 9], which is comparable with the outcomes of other reports. Complications have been reported following 6 % to 37 % of PAO cases [10]. These included heterotopic ossification, hematoma, injury of the lateral femoral cutaneous nerve, intra-articular osteotomy, malreduction, loss of fixation, nonunion, and acetabular fragment collapse [11–13]. Some are related to the osteotomy itself and others are related to the surgical approaches. Ischio-pubic stress fracture is one of these potential complications [14–16]. Stress concentration on the inferior limb of the pubis or ischial ramus is assumed to be the cause of ischio-pubic stress fracture, as the superior limb of the pubis is disconnected in PAO [14, 15]. This fracture has been reported to occur in 2.9–4.2 % of patients, however, very few papers described the risk factors of this fracture [14, 15]. We hypothesized that a greater degree of correction is associated with this fracture since greater correction leads to less overlap between the acetabulum and the remaining pelvis. The purpose of this study was to investigate the prevalence and risk factors of ischio-pubic fractures following PAO.
International Orthopaedics (SICOT)
Patients and methods Between January 2001 and December 2012, PAO was performed on 302 hips in 280 patients with symptomatic hip dysplasia in our institution. Among them, six hips in five patients who were not followed for more than 12 months after surgery or had neuromuscular disease were excluded. A total of 296 hips in 275 patients were enrolled in this study (Table 1). There were 30 men and 245 women. The mean age of the patients at operation was 42.4 (13–64) years old. The mean follow-up period was 46.1 (12–120) months. The mean body weight and body mass index (BMI) were 55.9 (29.8–90.8) kg and 22.6 (15.3–33.9) kg/m², respectively. The study was approved by and registered with the institutional review board. The indication for osteotomy was radiological evidence of acetabular dysplasia with a centre-edge (CE) angle< 20° [17] and pain in the hip that interfered with daily activities [8, 9] (Fig. 1a). The pre-operative OA stage was graded radiologically according to the Kellgren–Lawrence classification system [18, 19]. In all, 32 hips (10.8 %) were classified as grade 1 (doubtful sign of osteo-arthritic change: possible osteophytes and doubtful narrowing of the joint space); 211 (71.3 %) as grade 2 (mild osteoarthritis: definite osteophytes and possible narrowing of the joint space); and 53 (17.9 %) as grade 3 (moderate osteoarthritis: multiple osteophytes, definite narrowing of the joint space, some sclerosis, and possible deformity of bone contour). According to the classification system of Crowe et al. [20] based on the migration magnitude of the femoral head relative to the inter-teardrop line, all hips were classified as type 1—vertical subluxation measured from the inferior margin of the tear to the head–neck junction is
ORIGINAL PAPER
Ischio-pubic stress fracture after peri-acetabular osteotomy in patients with hip dysplasia Satoshi Hamai & Yasuharu Nakashima & Mio Akiyama & Umito Kuwashima & Takuaki Yamamoto & Goro Motomura & Masanobu Ohishi & Yukihide Iwamoto
Received: 10 April 2014 / Accepted: 4 May 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Ischio-pubic stress fracture is one of the potential complications after peri-acetabular osteotomy (PAO) in patients with hip dysplasia. The purpose of this study was to examine the prevalence of and risk factors for ischio-pubic fractures following PAO. Methods A total of 296 hips in 275 patients who underwent transposition osteotomy of the acetabulum between 2001 and 2012 were retrospectively reviewed. Patient characteristics and radiographic parameters were compared between patients with and without fracture. Results Fourteen ipsilateral hips (4.7 %) in 14 female patients had fracture of the inferior pubic ramus (11 hips) or the ischial ramus (three hips) on the same side as the surgery at an average of 4.6 weeks after PAO. Multivariate analysis indicated that younger age at operation (odds ratio of 1.43 per five years, p=0.0169) and greater degree of correction (odds ratio of 1.98 per five degrees, p=0.0005) were significantly associated with ischio-pubic fracture as independent risk factors. All fractures healed conservatively with partial weightbearing. Conclusions Younger female patients and greater deformity corrections increased the risk of ischio-pubic stress fracture after PAO.
Keywords Ischio-pubic fracture . Peri-acetabular osteotomy . Transpositional osteotomy of the acetabulum . Hip dysplasia S. Hamai (*) : Y. Nakashima : M. Akiyama : U. Kuwashima : T. Yamamoto : G. Motomura : M. Ohishi : Y. Iwamoto Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan e-mail: [email protected]
Introduction Peri-acetabular osteotomy (PAO) is accepted as an effective treatment for hip dysplasia in young to middle-aged patients [1–9]. PAO can improve acetabular coverage of the femoral head to restore joint congruity and stability, resulting in prevention of further OA deterioration. Previous studies have shown satisfactory intermediate to long-term results of PAO with excellent correction of deformity, pain relief, and restored function [1–7]. We have previously reported outcomes of transposition osteotomy of the acetabulum, a spherical osteotomy with a transtrochanteric approach. The survival rate with THA conversion or progress to the end stages of OA as the end points was 94 % at ten years after operation [8, 9], which is comparable with the outcomes of other reports. Complications have been reported following 6 % to 37 % of PAO cases [10]. These included heterotopic ossification, hematoma, injury of the lateral femoral cutaneous nerve, intra-articular osteotomy, malreduction, loss of fixation, nonunion, and acetabular fragment collapse [11–13]. Some are related to the osteotomy itself and others are related to the surgical approaches. Ischio-pubic stress fracture is one of these potential complications [14–16]. Stress concentration on the inferior limb of the pubis or ischial ramus is assumed to be the cause of ischio-pubic stress fracture, as the superior limb of the pubis is disconnected in PAO [14, 15]. This fracture has been reported to occur in 2.9–4.2 % of patients, however, very few papers described the risk factors of this fracture [14, 15]. We hypothesized that a greater degree of correction is associated with this fracture since greater correction leads to less overlap between the acetabulum and the remaining pelvis. The purpose of this study was to investigate the prevalence and risk factors of ischio-pubic fractures following PAO.
International Orthopaedics (SICOT)
Patients and methods Between January 2001 and December 2012, PAO was performed on 302 hips in 280 patients with symptomatic hip dysplasia in our institution. Among them, six hips in five patients who were not followed for more than 12 months after surgery or had neuromuscular disease were excluded. A total of 296 hips in 275 patients were enrolled in this study (Table 1). There were 30 men and 245 women. The mean age of the patients at operation was 42.4 (13–64) years old. The mean follow-up period was 46.1 (12–120) months. The mean body weight and body mass index (BMI) were 55.9 (29.8–90.8) kg and 22.6 (15.3–33.9) kg/m², respectively. The study was approved by and registered with the institutional review board. The indication for osteotomy was radiological evidence of acetabular dysplasia with a centre-edge (CE) angle< 20° [17] and pain in the hip that interfered with daily activities [8, 9] (Fig. 1a). The pre-operative OA stage was graded radiologically according to the Kellgren–Lawrence classification system [18, 19]. In all, 32 hips (10.8 %) were classified as grade 1 (doubtful sign of osteo-arthritic change: possible osteophytes and doubtful narrowing of the joint space); 211 (71.3 %) as grade 2 (mild osteoarthritis: definite osteophytes and possible narrowing of the joint space); and 53 (17.9 %) as grade 3 (moderate osteoarthritis: multiple osteophytes, definite narrowing of the joint space, some sclerosis, and possible deformity of bone contour). According to the classification system of Crowe et al. [20] based on the migration magnitude of the femoral head relative to the inter-teardrop line, all hips were classified as type 1—vertical subluxation measured from the inferior margin of the tear to the head–neck junction is
